JPS63290792A - Data-recording medium and production thereof - Google Patents

Abstract

PURPOSE:To obtain a data-recording medium having a high C/N and a simple construction and being excellent in recording sensitivity and recording efficiency, by introducing a rare gas into an amorphous film. CONSTITUTION:An information-recording medium comprises an amorphous recording film 2 containing a rare gas on a substrate 1. With the amorphous recording layer selectively heated by laser rays or the like, the film at the heated part is softened, and the rare gas incorporated in the film is gasified, resulting in a protruding deformation. With the protrudingly deformed parts as bubbles, data is recorded. A simple substance of a metal such as Zr, Hf, Nb, Zn, Cd, Ga, In, Tl, Pb, Sn and Ag or a semimetal such as B, C, Si, P, Ge, As, Se, Sb, Te and Bi, a combination of at least two of such simple substances or the like is used as a material for forming the amorphous recording film 2. The rare gas to be introduced into the recording film is one which does not chemically react with the metal or semimetal at the time of producing the recording film.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an information recording medium that can be optically recorded and reproduced, and a method for manufacturing the same. The present invention relates to an information recording medium on which is formed and a method for manufacturing the same.

[Summary of the invention]

By using an amorphous film containing a rare gas as a recording film, the present invention makes it possible to record and reproduce information by forming raised deformed portions (referred to as bubbles) by selective heating using laser light or the like. The aim is to provide a possible information recording medium.

Furthermore, the present invention simultaneously forms an amorphous film and mixes a rare gas by depositing a metal and/or a metalloid on a substrate in a plasma in which a rare gas is present, thereby forming an amorphous recording film containing a rare gas. can be efficiently produced.

[Conventional technology]

Optical recording systems have the advantage of being able to record and read without contact, being easy to handle, and being resistant to scratches and dust, as well as having a larger storage capacity than conventional magnetic recording systems. Because of this, it is expected to be used as a large-capacity memory.

Among these, the user can directly write and use it. There is a lot of interest in so-called write-once optical recording media, and in order to meet the demands for streak sensitivity, high stability, high quality, etc., research on recording materials in particular is being actively conducted.

As a write-once optical recording medium, information is recorded by forming a metal thin film mainly made of Te or an organic dye-based thin film on a substrate and irradiating it with a laser beam to form holes called pits. Optical recording media are known.

However, in the case of such an optical recording medium, an irregular bulge called a rim occurs at the periphery of the formed pit, which is a major cause of a decrease in C/N during reproduction.

Therefore, as a method for recording signals without forming pits, an optical recording medium has been proposed in which information is recorded by forming raised deformed portions called bubbles.

For example, in JP-A-56-12793, an organic intermediate layer and a gold light-absorbing layer are sequentially formed on a substrate, and the transparent organic intermediate layer is indirectly heated by local heating of the metallic light-absorbing layer. A write-once optical recording medium is disclosed in which recording is performed by elevating and deforming a metallic light absorption layer by gas generated therefrom to form bubbles.

However, in the above-mentioned optical recording medium, since the transparent organic intermediate layer is heated indirectly, the light utilization efficiency is extremely poor, and a very large amount of energy is required for recording. This results in the increase in the output power of the laser used and the increase in the size of the device, which poses a major obstacle to practical application.

Alternatively, in JP-A-56-65341, a metallic light-reflecting layer, a light-transmitting layer, and a metallic light-absorbing layer are sequentially formed on a substrate, and the light-transmitting layer is formed by locally heating the metallic light-absorbing layer on the surface. A write-once optical recording medium has been disclosed in which recording is performed by indirectly heating a gold light absorbing layer and elevating and deforming the gold light absorbing layer by gas generated thereby to form bubbles. In this optical recording medium, since a metallic light reflective layer is formed on the substrate, the light utilization efficiency is improved as disclosed in Japanese Patent Application Laid-Open No. 56-12793.
It is higher than that stated in the publication.

However, this optical recording medium has a problem in that the manufacturing process is complicated because it has a 3N structure. This causes an increase in the number of manufacturing steps, a decrease in yield, and an increase in manufacturing costs. In addition, in such a multilayer film structure, in order to improve recording sensitivity, it is necessary to optimize the refractive index and film thickness of each film under extremely strict conditions, which also makes it difficult to manufacture optical recording media. This is a factor that makes this possible.

Furthermore, in JP-A-61-178742,
An optical recording medium has been proposed in which a thin film in which fine metal particles and organic matter are dispersed in a metal carbide matrix is formed on a substrate, and the organic matter having a gas generating function is gasified by local heating of the thin film to form bubbles. .

Although this optical recording medium has a simple structure, it has a problem of low sensitivity. Therefore, attempts have been made to add hydrogen or oxygen to improve sensitivity, but this requires strict gas flow rate adjustment, which poses problems in mass production.
Problems include the fact that the gas used itself is dangerous, and because the recording film is an aggregate of fine metal particles, the generation of noise due to diffuse reflection by the grain boundaries of the fine particles is unavoidable.

[Problem that the invention seeks to solve]

As described above, all optical recording media that record information by forming raised deformed parts called bubbles remain unsatisfied with respect to recording efficiency, sensitivity, productivity, etc., and improvements are desired. has been done.

Therefore, the present invention was proposed in view of the above-mentioned conventional situation, and an object of the present invention is to provide an information recording medium having a high C/N and a simple structure, and having excellent recording sensitivity and recording efficiency. The purpose of the present invention is to provide an efficient manufacturing method for such information recording media.

Measures for Solving Problems] The inventors of the present invention have conducted intensive research over a long period of time in order to achieve the above-mentioned objective, and as a result, they have discovered that bubbles can be formed with high sensitivity by introducing a rare gas into an amorphous film. The present invention has been completed based on the discovery that this can be done.

That is, as shown in FIG. 1, the information recording medium of the present invention has an amorphous recording film (
2), and is characterized in that recording is performed by selectively heating the amorphous recording film (2) to raise the heated portion.

Furthermore, the manufacturing method of the present invention is characterized in that a metal and/or metalloid is deposited on a substrate in plasma in the presence of a rare gas to form an amorphous recording film containing the rare gas.

In the information recording medium of the present invention, the material of the substrate (1) is glass, lI! , etc. metals, various ceramics,
Examples include plastics such as polycarbonate. Note that guide grooves called groups may be formed in these bases (1).

On the other hand, the materials constituting the amorphous recording film (2) include:
Zr, Hf, Nb,
Zn, Cd, Ga, In.

Metals such as Tl, Pb, Sn, Ag, and B, C.

A single semimetal such as Si, P, Ge, As, Se, Sb, Te, Bi or a combination of two or more of these metals is used.

This amorphous recording film (2) contains these metals.

In addition to semimetals, rare gases are introduced, but the introduced rare gases are those that do not chemically react with these metals and semimetals when producing the recording film.
r, Ne, Xe, etc. Nitrogen cannot be used because it reacts with metals and metalloids during film formation.

The film thickness of the amorphous recording film (2) is preferably 50 Å or more. If the film thickness is less than 50 Å, it is difficult to form a uniform film. The upper limit is not particularly limited, but the recording sensitivity and bubble formation conditions Furthermore, in consideration of practicality such as productivity, the thickness is preferably 1000 Å or less. More preferably, it is 200 to 800 people.

The above-mentioned amorphous recording film (2) is produced by PVD (Pby-sical VD) using the metal or metalloid or both as a target in plasma in which the rare gas exists.
It is produced by performing apour deposition). If PVD is performed in plasma, the rare gas is easily incorporated into the film, and since the kinetic energy of atoms is large, the film tends to become an amorphous film when it reaches the substrate (1).

Suitable PVD methods include sputtering, ion blating, EcR<electron cyclotron resonance), and the like.

During PVD, the atmospheric gas pressure, that is, the gas pressure of the introduced rare gas, is 5X10-''~IX10-' To
The gas pressure of the rare gas is preferably in the range of rr.
If it is less than X 10-' Torr, there is a possibility that the rare gas taken into the amorphous recording film (2) will be insufficient, and the protrusion deformation will not occur sufficiently. Conversely, the gas pressure of the noble gas is I
If it exceeds Xl0-'Torr, it is difficult to perform good PVD.

As described above, when PVD is performed in a plasma where a rare gas exists, the rare gas collides with a target made of metal, metalloid, or both, and the atoms constituting the target are ejected and attached to the substrate (1). Those that arrive are deposited on the substrate (1). At the same time, rare gas is also taken into the film.

[Effect]

When an amorphous recording film containing a rare gas is selectively heated with a laser beam or the like, the film in the heated portion is softened and the rare gas taken into the film is gasified and deformed into a raised shape.

In the information recording medium of the present invention, information is recorded using the raised deformed portion as a bubble.

Furthermore, if PVD is performed in a plasma containing rare gases,
Atoms constituting the target are ejected to form a film on the substrate, and at the same time, a rare gas in the PVD atmosphere is introduced into the film.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows a schematic configuration of the manufacturing apparatus used in carrying out this example.

This manufacturing apparatus includes a substrate holder (1) with a substrate (13) mounted in a vacuum chamber (11) equipped with an exhaust device (18).
2), and a target (14) connected to a high frequency electric current a (15). A gas cylinder (17) filled with rare gas is connected to the vacuum chamber (11) via a valve mechanism (16).

An information recording medium was manufactured using a manufacturing apparatus having such a configuration through the following steps. In this example, a polycarbonate disk with groups (guide grooves) was used as the base (13). The material of the target (14) is selected considering the following factors: 1) it is easy to form an amorphous film; 1) it has an appropriate reflectance (20 to 70%); and 2) it has excellent corrosion resistance. Here, Agr. Ins. Gem
. (The numerical value represents the composition in atomic percent.)

First, the inside of the vacuum chamber (11) of the above-mentioned manufacturing apparatus was heated to 10-'To
It was degassed to below rr.

Next, the valve (16) was opened to introduce a predetermined amount of rare gas into the vacuum chamber (11). In this case, bubbles are formed or collapsed depending on the amount of rare gas contained in the film, so the amount of introduced rare gas must be set appropriately, but this depends on the target material forming the film and the plasma generation. It can be controlled by the noble gas gas pressure in the internal vacuum chamber (11).

In this example, Ar is used as the rare gas, and the gas pressure is IX 1
0-” Torr.

When the inside of the vacuum chamber (11) reaches a predetermined pressure due to the rare gas, high frequency power is applied to the target (14) and the base (
In this example, a high frequency power of 100 W was applied to generate plasma between the target (13) and the target (14).

As a result, the rare gas collides with the target (14), the atoms constituting the target (14) are ejected and deposited on the substrate (13), and at the same time the rare gas is incorporated into the film. Film thickness: 800 mm after 5 minutes from start
A human amorphous recording film was formed.

The information recording medium produced in this way was
Rotated at s (linear velocity 1.3 m/5ec), output 2.5 m V focused to a spot size of 1.6 μm.
, a semiconductor laser with a pulse intensity of 5ec (wavelength: 83On)
+s) was irradiated from the substrate (13) side for recording.

As a result, as shown in FIG. 3, it was confirmed that the film underwent upward deformation and bubbles were formed.

According to scanning electron microscopy, the recording part has a diameter of 1.5 μm.
, it has been confirmed that the bubble is 0.15 μm in height.

Next, a continuous beam with an output of 0.3 mW was irradiated from the surface of the base (13) to perform reproduction. At this time, the C/N of the reproduced signal
A good result of 55 dB was obtained.

As a comparative example, an Ag-In-C;efN film containing no rare gas was formed by vacuum evaporation under the same conditions as in this example,
Recording was performed under the same conditions, but no bubbles were formed.

〔Effect of the invention〕

As is clear from the above explanation, since the information recording medium of the present invention uses an amorphous film containing rare gas as the recording film, bubbles can be formed with high sensitivity by irradiation with laser light, etc., and recording efficiency can be improved. It is possible to provide an information recording medium with excellent sensitivity and sensitivity.

Further, in the information recording medium of the present invention, since the recording film is an amorphous film, noise due to grain boundaries does not occur, and a high C/N can be obtained.

Furthermore, the information recording medium of the present invention has a simple structure and is useful in terms of productivity, manufacturing cost, etc.

Furthermore, according to the manufacturing method of the present invention, the formation of the amorphous film and the introduction of the rare gas into the film can be performed at the same time, and the formation of the recording film is simplified into one step, which improves the yield.
It becomes possible to reduce manufacturing costs.

Further, according to the manufacturing method of the present invention, an amorphous film can be easily formed even if the material is easily crystallized, and a recording film with low noise and capable of high-density recording can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of essential parts showing an example of the configuration of an information recording medium to which the present invention is applied. 2 is a block diagram schematically showing an example of a manufacturing apparatus used in manufacturing an amorphous recording film. FIG. 3 is an electron micrograph (magnification: 500 times) showing the structure of particles formed on an amorphous recording film. 1 ... Substrate 2 ... Amorphous recording film 2

Claims (2)

[Claims] (1) An information recording medium comprising an amorphous recording film containing a rare gas on a substrate, and recording is performed by selectively heating the amorphous recording film to raise a heated portion. (2) A method for manufacturing an information recording medium, which comprises depositing a metal and/or a metalloid on a substrate in plasma in the presence of a rare gas to form an amorphous recording film containing the rare gas.